package com.yxx.queue;

import java.util.Scanner;

public class ArrayQueueDemo {
    public static void main(String[] args) {
        ArrayQueue queue = new ArrayQueue(3);
        char key=' '; //接受用户输入
        Scanner scanner = new Scanner(System.in);
        Boolean loop=true;
        while (loop){
            System.out.println("s(show):显示队列");
            System.out.println("e(exit):退出");
            System.out.println("a(add):添加数据到队列");
            System.out.println("g(get):取出队列数据");
            System.out.println("h(head):查看队列头的数据");
            key=scanner.next().charAt(0);
            switch (key){
                case 's':
                    queue.listQueue();
                    break;
                case 'a':
                    System.out.println("输入一个数：");
                    int value=scanner.nextInt();
                    queue.addQueue(value);
                    break;
                case 'g':
                    try {
                        int res = queue.getQueue();
                        System.out.printf("取出的数据是：%d\n",res);
                    }catch (Exception e){
                        System.out.println(e.getMessage());
                    }
                    break;
                case 'h':
                    try {
                        int res = queue.headQueue();
                        System.out.printf("头部数据为：%d\n",res);
                    }catch (Exception e){
                        System.out.println(e.getMessage());
                    }
                    break;
                case 'e':
                    scanner.close();
                    loop=false;
                    break;
                default:
                    break;

            }
        }
        System.out.println("程序退出！");

    }
}
//使用数组模拟队列-编写一个ArrayQueue类
class ArrayQueue{
    private int maxSize;//表示数组的最大容量
    private int front; //队列头
    private int rear; //队列尾
    private int[] arr; //该数据用于存放数据，模拟队列

    public ArrayQueue(int arrMaxSize){
        maxSize=arrMaxSize;
        arr=new int[maxSize];
        front=-1; //只想队列头部，分析出front是指向队列投的前一个位置
        rear=-1; //指向队列尾，指向队列尾的数据(即就是队列最后一个数据)
    }

    //判断队列是否满
    public boolean isFull(){
        return rear==maxSize-1;
    }

    //判断队列是否为空
    public boolean isEmpty(){
        return rear==front;
    }

    //入队
    public void addQueue(int n){
        //判断队列是否满
        if(isFull()){
            System.out.println("sorry,the queue is full!");
            return;
        }
        rear++;
        arr[rear]=n;
    }

    //出队
    public int getQueue(){
        //判断队列是否为空
        if(isEmpty()){
            throw new RuntimeException("the queue is empty!");
        }
        front++; //后移
        return arr[front];
    }

    //展示队列的所有数据
    public void listQueue(){
        if(isEmpty()){
            System.out.println("the queue is empty");
            return;
        }
        System.out.println("the queue is:");
        for(int i=0;i<arr.length;i++){
            System.out.printf("arr[%d]=%d\n",i,arr[i]);
        }
    }
    //展示队列头的数据
    public int headQueue(){
        if(isEmpty()){
            throw new RuntimeException("he queue is empty");
        }
        return arr[front+1];
    }
}
